In general, most of known printing apparatus of this kind have been such that the printed output is of a definite format, and, upon completion of printing, it generally sends out the printed output with a paper transfer mechanism such that a perforated line of recording paper comes out of the apparatus, allowing the printed output to be cut along the perforated line.
Accordingly, some apparatus have been proposed in recent years in which the printed output is transferred to a discharge port by using a transfer means, etc. after it is cut and while the printing is stopped for a moment within the apparatus, as shown in FIG. 26, in order to adapt to printed output of an irregular shape (varied in length) and to avoid paper jams due to consequent strain of the recording paper during the printing. That is, a numeral 51 in the figure represents rolled paper which is arranged so that it is cut in a predetermined length by a cutter unit 53 and transferred to a discharge port 55 by a presenter 54 after it is printed by a printer unit 52. Also, numeral 56 represents a rolled-paper holder for rotatably supporting the rolled paper 51, and numerals 57 and 58 are a roller and a printer head, respectively, representing structural elements of the printer unit 52.
With the above described structure of the prior art, a leading end of the rolled paper 51 held in the rolled-paper holder 56 needs to be inserted into a feeding port (not shown in the figure) of the printer unit 52 when the rolled paper 51 is reset in the printer unit 52 for replacement of the rolled paper 51, or after removal of jammed paper, etc. In doing this task, however, the leading edge of the rolled paper 51 held in the rolled paper holder 56 can not be simply and easily inserted into the feeding port of the printer unit 52, and jammed paper between the rolled paper 51 and the printer unit 52 can not be readily removed, because of a very tight space between the rolled paper 51 and the printer unit 52 in the prior art structure.
There has been a fear that the rolled paper 51 is inadvertently rumpled or torn if the rolled paper 51 could not be easily set in position. Also, there has been another fear that a part of the jammed paper may be left behind in the printing apparatus if the jammed paper can not be removed easily. They have been causes leading to other paper jams. Widening the space between the rolled paper 51 and the printer unit 52 could resolve this problem, but it would raise a new problem in that the dimensional reduction of the apparatus is restricted.
Also, the structure of the prior art has frequently caused paper jams in the transfer presenter 54. Although there is a way to prevent it, in that the transfer presenter 54 is disused, and recording papers are freely dropped under their own weight to lead them to the discharge opening after printing, this poses a problem with papers that fly out of the discharge opening by impetus of the dropping.
Furthermore, the structure of the prior art tends to cause the rolled paper 51 to stick to a surface of the roller 57 or the printer head 58 during a long stand-by time, or if it is used in an environment of high temperature, high humidity, low temperature, low humidity, etc. regardless of the stand-by period, so as to result in a failure of feeding the paper in the succeeding printing operation and to become liable to cause a paper jam. Also, there have been cases in which the paper transferring operation is impaired due to oxidation, corrosion, hardening of grease, etc. of components such as a gear, an axle, a bearing, etc. that constitute a paper transfer mechanism. There have also been impairments with the operation of a cutter mechanism having a similar component structure.
The present invention is intended to solve the above problems, and it aims at providing a printing apparatus of a small size that facilitates the replacement of rolled paper, removal of jammed papers, etc. with a considerably simple structure.
The invention also aims at providing a printing apparatus of considerably simple structure that reliably delivers a printed output to a discharge port without causing a paper jam, even for printed output of an irregular shape (varied in length).
The invention further aims at providing a highly reliable printing apparatus which prevents a paper jam in a succeeding printing operation, and avoids impairment of the operation of the paper transfer mechanism and the cutter mechanism, even under such severe conditions as an extended stand-by time and a use environment of high temperature, high humidity, low temperature, low humidity, etc.